What You Need Before You Start

An under-cabinet range hood mounts flat against the underside of your kitchen cabinet, directly above your cooktop. Installation takes four to six hours for a straightforward job, longer if you need to run new ductwork or electrical lines. You will need basic hand tools, a drill, a level, and either a helper or a way to support the hood while you work—it is heavy and awkward to hold alone.

Before you buy, measure the width of your cooktop and check your cabinet height. Most hoods are 30, 36, or 42 inches wide. The hood should extend at least 3 inches beyond the cooktop on each side. Measure the distance from your cooktop surface to the bottom of the cabinet; standard clearance is 24 to 30 inches, though your hood manual will specify the minimum.

Check what is above the cabinet. If there is a soffit or another cabinet, you may not have room for ductwork. If you are venting outside, trace the path from the hood to the exterior wall—the shorter and straighter the duct run, the better the hood performs. If you cannot vent outside, you will need a recirculating hood with charcoal filters instead.

Key Takeaways

  • Measure your cooktop width and cabinet height before purchasing; the hood must extend 3 inches beyond the cooktop on each side and sit 24 to 30 inches above the cooking surface.
  • Decide whether you will vent to the outside or use a recirculating hood with filters, because this determines what ductwork and electrical connections you need.
  • Turn off power at the breaker before running any new electrical lines, and use a stud finder to locate cabinet framing so your mounting bolts anchor into solid wood.
  • The hood must be level side to side and front to back, or grease will pool and the unit may not drain properly.
  • Have a helper support the hood while you drill and bolt it in place; trying to hold it alone while working overhead is unsafe and will result in crooked installation.

Gather Your Tools and Materials

You will need a drill with both a regular bit set and a spade bit (for larger holes), a level, a stud finder, a tape measure, a pencil, and a socket wrench or adjustable wrench to fit your mounting bolts. Have a helper on hand—this is not a one-person job. Wear safety glasses because you will be working overhead and debris falls.

Check your hood box for the mounting template, which is usually a cardboard or plastic sheet showing where to drill. If it is missing, the manual will have dimensions. You will also need the ductwork that came with the hood (or that you purchased separately), duct tape or metal clamps, and any electrical supplies your installation requires. If you are running new power, you will need appropriate gauge wire, a junction box, and possibly a new breaker—this part should be done by a licensed electrician if you are not experienced with electrical work.

Turn Off Power and Locate the Framing

If your hood will plug into an existing outlet, turn off that circuit at the breaker panel. If you are running new electrical, turn off the main breaker or have an electrician do the work. Never work on live circuits.

Use a stud finder to locate the wooden framing inside your cabinet. Most cabinets have a solid frame at the top and sides. Mark the stud locations with a pencil. Your mounting bolts must go into these studs, not into the thin plywood or veneer of the cabinet box—if they do not anchor into solid wood, the hood will sag or fall. The mounting template will show you where the bolt holes go; align it with your stud marks and adjust if necessary so the bolts land on framing.

Drill Mounting Holes and Prepare the Cabinet

Mark the hole locations on the underside of the cabinet using the template. Drill pilot holes first—these are small holes that guide your larger drill bit and prevent the wood from splitting. Use a bit slightly smaller than your mounting bolts. Drill straight up into the cabinet; if the bit wanders, your holes will not line up and the hood will sit crooked.

If your hood will vent outside, you also need to drill a hole for the ductwork to pass through the cabinet or wall. This is usually a 6-inch or 7-inch hole, depending on your duct diameter. A spade bit or hole saw makes this easier than a regular drill bit. Drill from inside the cabinet so you can see where the bit comes through and avoid hitting plumbing or electrical lines on the other side. If you are unsure what is behind the wall, cut a small exploratory hole first or use a stud finder that detects wires and pipes.

Install the Mounting Bracket and find the Hood

Have your helper hold the hood in position while you insert the mounting bolts through the holes you drilled. Start the bolts by hand so they do not cross-thread. Once all bolts are started, tighten them gradually in a crisscross pattern—tighten the top left, then bottom right, then top right, then bottom left—so the hood pulls up evenly and does not tilt.

Use a level to check that the hood is straight side to side and front to back before you fully tighten. If it is not level, loosen the bolts slightly, adjust the hood, and re-tighten. Do not skip this step. A tilted hood will not drain grease properly, and the unit may rattle or vibrate during use. Once the hood is level and tight, have your helper release it and make sure it does not move or sag.

Connect the Ductwork and Electrical

Slide the duct onto the outlet on the back or bottom of the hood. If the fit is loose, wrap the joint with duct tape or use a metal hose clamp to hold it tight. Run the duct toward your exterior wall or to your recirculation filter box, keeping the run as straight as possible. Avoid sharp bends, which slow airflow and reduce the hood's ability to capture smoke and steam. If you must bend the duct, use a 45-degree elbow rather than a 90-degree one.

For exterior venting, drill through the wall to the outside and install a vent cap on the exterior side. The cap should have a damper that closes when the hood is off, preventing cold air from flowing back into the kitchen. Seal around the duct where it exits the wall with caulk or foam sealant.

Plug the hood into the outlet or have an electrician connect it to a new circuit if required. Test the hood on low, medium, and high speed before you close up the cabinet. Listen for rattling or unusual noise, and check that air is moving out of the ductwork or through the filter. If the airflow is weak, check that the duct is not kinked and that the vent cap damper opens fully.

Seal and Finish

Once the hood is running correctly, seal any gaps between the hood and the cabinet with caulk that matches your cabinet finish. This prevents grease and steam from escaping into the cabinet space above. Let the caulk dry fully before you use the hood.

Install the filter or filters according to your hood manual. Charcoal filters in recirculating hoods typically last three to six months before they need replacement. Mesh or baffle filters in vented hoods should be cleaned monthly by running them through the dishwasher or soaking them in hot soapy water. A clean filter keeps the hood running at full power and prevents grease buildup inside the ductwork.

Frequently Asked Questions

What if I cannot find studs in the right spot for the mounting bolts?

You may need to move the hood slightly left or right so the bolts land on framing. Check your manual to see how much adjustment is allowed. If the hood cannot move enough to hit studs, you can use heavy-duty toggle bolts or expansion anchors rated for the hood's weight, but these are less reliable than bolts into solid wood. A licensed carpenter can also reinforce the cabinet framing if needed.

Can I install an under-cabinet hood if my cabinet is not deep enough?

If the hood does not fit between the cabinet and the cooktop, you have two options: install a wall-mounted hood on the wall above the cooktop instead, or install a downdraft hood that pulls air down through the cooktop surface. Both are different products and require different installation steps. Measure carefully before you buy.

Do I need a new electrical circuit for the hood?

Most under-cabinet hoods draw 300 to 600 watts and can plug into a standard kitchen outlet. If your outlet is already in use by another appliance, you may need a dedicated circuit. Check your hood manual for the electrical requirements and have an electrician assess your kitchen if you are unsure.

What if my ductwork is too long or has too many bends?

Long or kinked ductwork reduces airflow and makes the hood less effective. If your run is longer than 25 feet or has more than four 90-degree bends, consider upgrading to a more powerful hood or installing a booster fan in the duct to push air outside. A booster fan adds cost but solves weak airflow problems caused by long duct runs.

How do I know if the hood is venting properly?

Turn the hood on high and hold a piece of tissue paper near the front edge. The paper should be pulled toward the hood. If it is not, check that the vent cap damper opens fully, the duct is not kinked, and the filter is clean. If airflow is still weak after checking these, the duct may be too long or the hood may be undersized for your cooktop.